/**
  * @file
 *
 * 6LowPAN output for IPv6. Uses ND tables for link-layer addressing. Fragments packets to 6LowPAN units.
 */

/*
 * Copyright (c) 2015 Inico Technologies Ltd.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * This file is part of the lwIP TCP/IP stack.
 *
 * Author: Ivan Delamer <delamer@inicotech.com>
 *
 *
 * Please coordinate changes and requests with Ivan Delamer
 * <delamer@inicotech.com>
 */

/**
 * @defgroup sixlowpan 6LowPAN netif
 * @ingroup addons
 * 6LowPAN netif implementation
 */

#include "netif/lowpan6.h"

#if LWIP_IPV6 && LWIP_6LOWPAN

#include "lwip/ip.h"
#include "lwip/pbuf.h"
#include "lwip/ip_addr.h"
#include "lwip/netif.h"
#include "lwip/nd6.h"
#include "lwip/mem.h"
#include "lwip/udp.h"
#include "lwip/tcpip.h"
#include "lwip/snmp.h"

#include <string.h>

struct ieee_802154_addr {
	u8_t addr_len;
	u8_t addr[8];
};

/** This is a helper struct.
 */
struct lowpan6_reass_helper {
	struct pbuf* pbuf;
	struct lowpan6_reass_helper* next_packet;
	u8_t timer;
	struct ieee_802154_addr sender_addr;
	u16_t datagram_size;
	u16_t datagram_tag;
};

static struct lowpan6_reass_helper* reass_list;

#if LWIP_6LOWPAN_NUM_CONTEXTS > 0
	static ip6_addr_t lowpan6_context[LWIP_6LOWPAN_NUM_CONTEXTS];
#endif

static u16_t ieee_802154_pan_id;

static const struct ieee_802154_addr ieee_802154_broadcast = {2, {0xff, 0xff}};

#if LWIP_6LOWPAN_INFER_SHORT_ADDRESS
static struct ieee_802154_addr short_mac_addr = {2, {0, 0}};
#endif /* LWIP_6LOWPAN_INFER_SHORT_ADDRESS */

static err_t dequeue_datagram(struct lowpan6_reass_helper* lrh);

/**
 * Periodic timer for 6LowPAN functions:
 *
 * - Remove incomplete/old packets
 */
void
lowpan6_tmr(void)
{
	struct lowpan6_reass_helper* lrh, *lrh_temp;

	lrh = reass_list;

	while(lrh != NULL) {
		lrh_temp = lrh->next_packet;

		if((--lrh->timer) == 0) {
			dequeue_datagram(lrh);
			pbuf_free(lrh->pbuf);
			mem_free(lrh);
		}

		lrh = lrh_temp;
	}
}

/**
 * Removes a datagram from the reassembly queue.
 **/
static err_t
dequeue_datagram(struct lowpan6_reass_helper* lrh)
{
	struct lowpan6_reass_helper* lrh_temp;

	if(reass_list == lrh) {
		reass_list = reass_list->next_packet;
	} else {
		lrh_temp = reass_list;

		while(lrh_temp != NULL) {
			if(lrh_temp->next_packet == lrh) {
				lrh_temp->next_packet = lrh->next_packet;
				break;
			}

			lrh_temp = lrh_temp->next_packet;
		}
	}

	return ERR_OK;
}

static s8_t
lowpan6_context_lookup(const ip6_addr_t* ip6addr)
{
	s8_t i;

	for(i = 0; i < LWIP_6LOWPAN_NUM_CONTEXTS; i++) {
		if(ip6_addr_netcmp(&lowpan6_context[i], ip6addr)) {
			return i;
		}
	}

	return -1;
}

/* Determine compression mode for unicast address. */
static s8_t
lowpan6_get_address_mode(const ip6_addr_t* ip6addr, const struct ieee_802154_addr* mac_addr)
{
	if(mac_addr->addr_len == 2) {
		if((ip6addr->addr[2] == (u32_t)PP_HTONL(0x000000ff)) &&
		        ((ip6addr->addr[3]  & PP_HTONL(0xffff0000)) == PP_NTOHL(0xfe000000))) {
			if((ip6addr->addr[3]  & PP_HTONL(0x0000ffff)) == lwip_ntohl((mac_addr->addr[0] << 8) | mac_addr->addr[1])) {
				return 3;
			}
		}
	} else if(mac_addr->addr_len == 8) {
		if((ip6addr->addr[2] == lwip_ntohl(((mac_addr->addr[0] ^ 2) << 24) | (mac_addr->addr[1] << 16) | mac_addr->addr[2] << 8 | mac_addr->addr[3])) &&
		        (ip6addr->addr[3] == lwip_ntohl((mac_addr->addr[4] << 24) | (mac_addr->addr[5] << 16) | mac_addr->addr[6] << 8 | mac_addr->addr[7]))) {
			return 3;
		}
	}

	if((ip6addr->addr[2] == PP_HTONL(0x000000ffUL)) &&
	        ((ip6addr->addr[3]  & PP_HTONL(0xffff0000)) == PP_NTOHL(0xfe000000UL))) {
		return 2;
	}

	return 1;
}

/* Determine compression mode for multicast address. */
static s8_t
lowpan6_get_address_mode_mc(const ip6_addr_t* ip6addr)
{
	if((ip6addr->addr[0] == PP_HTONL(0xff020000)) &&
	        (ip6addr->addr[1] == 0) &&
	        (ip6addr->addr[2] == 0) &&
	        ((ip6addr->addr[3]  & PP_HTONL(0xffffff00)) == 0)) {
		return 3;
	} else if(((ip6addr->addr[0] & PP_HTONL(0xff00ffff)) == PP_HTONL(0xff000000)) &&
	          (ip6addr->addr[1] == 0)) {
		if((ip6addr->addr[2] == 0) &&
		        ((ip6addr->addr[3]  & PP_HTONL(0xff000000)) == 0)) {
			return 2;
		} else if((ip6addr->addr[2]  & PP_HTONL(0xffffff00)) == 0) {
			return 1;
		}
	}

	return 0;
}

/*
 * Encapsulates data into IEEE 802.15.4 frames.
 * Fragments an IPv6 datagram into 6LowPAN units, which fit into IEEE 802.15.4 frames.
 * If configured, will compress IPv6 and or UDP headers.
 * */
static err_t
lowpan6_frag(struct netif* netif, struct pbuf* p, const struct ieee_802154_addr* src, const struct ieee_802154_addr* dst)
{
	struct pbuf* p_frag;
	u16_t frag_len, remaining_len;
	u8_t* buffer;
	u8_t ieee_header_len;
	u8_t lowpan6_header_len;
	s8_t i;
	static u8_t frame_seq_num;
	static u16_t datagram_tag;
	u16_t datagram_offset;
	err_t err = ERR_IF;

	/* We'll use a dedicated pbuf for building 6LowPAN fragments. */
	p_frag = pbuf_alloc(PBUF_RAW, 127, PBUF_RAM);

	if(p_frag == NULL) {
		MIB2_STATS_NETIF_INC(netif, ifoutdiscards);
		return ERR_MEM;
	}

	/* Write IEEE 802.15.4 header. */
	buffer  = (u8_t*)p_frag->payload;
	ieee_header_len = 0;

	if(dst == &ieee_802154_broadcast) {
		buffer[ieee_header_len++] = 0x01; /* data packet, no ack required. */
	} else {
		buffer[ieee_header_len++] = 0x21; /* data packet, ack required. */
	}

	buffer[ieee_header_len] = (0x00 << 4); /* 2003 frame version */
	buffer[ieee_header_len] |= (dst->addr_len == 2) ? (0x02 << 2) : (0x03 << 2); /* destination addressing mode  */
	buffer[ieee_header_len] |= (src->addr_len == 2) ? (0x02 << 6) : (0x03 << 6); /* source addressing mode */
	ieee_header_len++;
	buffer[ieee_header_len++] = frame_seq_num++;

	buffer[ieee_header_len++] = ieee_802154_pan_id & 0xff; /* pan id */
	buffer[ieee_header_len++] = (ieee_802154_pan_id >> 8) & 0xff; /* pan id */
	i = dst->addr_len;

	while(i-- > 0) {
		buffer[ieee_header_len++] = dst->addr[i];
	}

	buffer[ieee_header_len++] = ieee_802154_pan_id & 0xff; /* pan id */
	buffer[ieee_header_len++] = (ieee_802154_pan_id >> 8) & 0xff; /* pan id */
	i = src->addr_len;

	while(i-- > 0) {
		buffer[ieee_header_len++] = src->addr[i];
	}

#if LWIP_6LOWPAN_IPHC
	/* Perform 6LowPAN IPv6 header compression according to RFC 6282 */
	{
		struct ip6_hdr* ip6hdr;

		/* Point to ip6 header and align copies of src/dest addresses. */
		ip6hdr = (struct ip6_hdr*)p->payload;
		ip_addr_copy_from_ip6(ip_data.current_iphdr_dest, ip6hdr->dest);
		ip_addr_copy_from_ip6(ip_data.current_iphdr_src, ip6hdr->src);

		/* Basic length of 6LowPAN header, set dispatch and clear fields. */
		lowpan6_header_len = 2;
		buffer[ieee_header_len] = 0x60;
		buffer[ieee_header_len + 1] = 0;

		/* Determine whether there will be a Context Identifier Extension byte or not.
		* If so, set it already. */
#if LWIP_6LOWPAN_NUM_CONTEXTS > 0
		buffer[ieee_header_len + 2] = 0;

		i = lowpan6_context_lookup(ip_2_ip6(&ip_data.current_iphdr_src));

		if(i >= 0) {
			/* Stateful source address compression. */
			buffer[ieee_header_len + 1] |= 0x40;
			buffer[ieee_header_len + 2] |= (i & 0x0f) << 4;
		}

		i = lowpan6_context_lookup(ip_2_ip6(&ip_data.current_iphdr_dest));

		if(i >= 0) {
			/* Stateful destination address compression. */
			buffer[ieee_header_len + 1] |= 0x04;
			buffer[ieee_header_len + 2] |= i & 0x0f;
		}

		if(buffer[ieee_header_len + 2] != 0x00) {
			/* Context identifier extension byte is appended. */
			buffer[ieee_header_len + 1] |= 0x80;
			lowpan6_header_len++;
		}

#endif /* LWIP_6LOWPAN_NUM_CONTEXTS > 0 */

		/* Determine TF field: Traffic Class, Flow Label */
		if(IP6H_FL(ip6hdr) == 0) {
			/* Flow label is elided. */
			buffer[ieee_header_len] |= 0x10;

			if(IP6H_TC(ip6hdr) == 0) {
				/* Traffic class (ECN+DSCP) elided too. */
				buffer[ieee_header_len] |= 0x08;
			} else {
				/* Traffic class (ECN+DSCP) appended. */
				buffer[ieee_header_len + lowpan6_header_len++] = IP6H_TC(ip6hdr);
			}
		} else {
			if(((IP6H_TC(ip6hdr) & 0x3f) == 0)) {
				/* DSCP portion of Traffic Class is elided, ECN and FL are appended (3 bytes) */
				buffer[ieee_header_len] |= 0x08;

				buffer[ieee_header_len + lowpan6_header_len] = IP6H_TC(ip6hdr) & 0xc0;
				buffer[ieee_header_len + lowpan6_header_len++] |= (IP6H_FL(ip6hdr) >> 16) & 0x0f;
				buffer[ieee_header_len + lowpan6_header_len++] = (IP6H_FL(ip6hdr) >> 8) & 0xff;
				buffer[ieee_header_len + lowpan6_header_len++] = IP6H_FL(ip6hdr) & 0xff;
			} else {
				/* Traffic class and flow label are appended (4 bytes) */
				buffer[ieee_header_len + lowpan6_header_len++] = IP6H_TC(ip6hdr);
				buffer[ieee_header_len + lowpan6_header_len++] = (IP6H_FL(ip6hdr) >> 16) & 0x0f;
				buffer[ieee_header_len + lowpan6_header_len++] = (IP6H_FL(ip6hdr) >> 8) & 0xff;
				buffer[ieee_header_len + lowpan6_header_len++] = IP6H_FL(ip6hdr) & 0xff;
			}
		}

		/* Compress NH?
		* Only if UDP for now. @todo support other NH compression. */
		if(IP6H_NEXTH(ip6hdr) == IP6_NEXTH_UDP) {
			buffer[ieee_header_len] |= 0x04;
		} else {
			/* append nexth. */
			buffer[ieee_header_len + lowpan6_header_len++] = IP6H_NEXTH(ip6hdr);
		}

		/* Compress hop limit? */
		if(IP6H_HOPLIM(ip6hdr) == 255) {
			buffer[ieee_header_len] |= 0x03;
		} else if(IP6H_HOPLIM(ip6hdr) == 64) {
			buffer[ieee_header_len] |= 0x02;
		} else if(IP6H_HOPLIM(ip6hdr) == 1) {
			buffer[ieee_header_len] |= 0x01;
		} else {
			/* append hop limit */
			buffer[ieee_header_len + lowpan6_header_len++] = IP6H_HOPLIM(ip6hdr);
		}

		/* Compress source address */
		if(((buffer[ieee_header_len + 1] & 0x40) != 0) ||
		        (ip6_addr_islinklocal(ip_2_ip6(&ip_data.current_iphdr_src)))) {
			/* Context-based or link-local source address compression. */
			i = lowpan6_get_address_mode(ip_2_ip6(&ip_data.current_iphdr_src), src);
			buffer[ieee_header_len + 1] |= (i & 0x03) << 4;

			if(i == 1) {
				MEMCPY(buffer + ieee_header_len + lowpan6_header_len, (u8_t*)p->payload + 16, 8);
				lowpan6_header_len += 8;
			} else if(i == 2) {
				MEMCPY(buffer + ieee_header_len + lowpan6_header_len, (u8_t*)p->payload + 22, 2);
				lowpan6_header_len += 2;
			}
		} else if(ip6_addr_isany(ip_2_ip6(&ip_data.current_iphdr_src))) {
			/* Special case: mark SAC and leave SAM=0 */
			buffer[ieee_header_len + 1] |= 0x40;
		} else {
			/* Append full address. */
			MEMCPY(buffer + ieee_header_len + lowpan6_header_len, (u8_t*)p->payload + 8, 16);
			lowpan6_header_len += 16;
		}

		/* Compress destination address */
		if(ip6_addr_ismulticast(ip_2_ip6(&ip_data.current_iphdr_dest))) {
			/* @todo support stateful multicast address compression */

			buffer[ieee_header_len + 1] |= 0x08;

			i = lowpan6_get_address_mode_mc(ip_2_ip6(&ip_data.current_iphdr_dest));
			buffer[ieee_header_len + 1] |= i & 0x03;

			if(i == 0) {
				MEMCPY(buffer + ieee_header_len + lowpan6_header_len, (u8_t*)p->payload + 24, 16);
				lowpan6_header_len += 16;
			} else if(i == 1) {
				buffer[ieee_header_len + lowpan6_header_len++] = ((u8_t*)p->payload)[25];
				MEMCPY(buffer + ieee_header_len + lowpan6_header_len, (u8_t*)p->payload + 35, 5);
				lowpan6_header_len += 5;
			} else if(i == 2) {
				buffer[ieee_header_len + lowpan6_header_len++] = ((u8_t*)p->payload)[25];
				MEMCPY(buffer + ieee_header_len + lowpan6_header_len, (u8_t*)p->payload + 37, 3);
				lowpan6_header_len += 3;
			} else if(i == 3) {
				buffer[ieee_header_len + lowpan6_header_len++] = ((u8_t*)p->payload)[39];
			}
		} else if(((buffer[ieee_header_len + 1] & 0x04) != 0) ||
		          (ip6_addr_islinklocal(ip_2_ip6(&ip_data.current_iphdr_dest)))) {
			/* Context-based or link-local destination address compression. */
			i = lowpan6_get_address_mode(ip_2_ip6(&ip_data.current_iphdr_dest), dst);
			buffer[ieee_header_len + 1] |= i & 0x03;

			if(i == 1) {
				MEMCPY(buffer + ieee_header_len + lowpan6_header_len, (u8_t*)p->payload + 32, 8);
				lowpan6_header_len += 8;
			} else if(i == 2) {
				MEMCPY(buffer + ieee_header_len + lowpan6_header_len, (u8_t*)p->payload + 38, 2);
				lowpan6_header_len += 2;
			}
		} else {
			/* Append full address. */
			MEMCPY(buffer + ieee_header_len + lowpan6_header_len, (u8_t*)p->payload + 24, 16);
			lowpan6_header_len += 16;
		}

		/* Move to payload. */
		pbuf_header(p, -IP6_HLEN);

		/* Compress UDP header? */
		if(IP6H_NEXTH(ip6hdr) == IP6_NEXTH_UDP) {
			/* @todo support optional checksum compression */

			buffer[ieee_header_len + lowpan6_header_len] = 0xf0;

			/* determine port compression mode. */
			if((((u8_t*)p->payload)[0] == 0xf0) && ((((u8_t*)p->payload)[1] & 0xf0) == 0xb0) &&
			        (((u8_t*)p->payload)[2] == 0xf0) && ((((u8_t*)p->payload)[3] & 0xf0) == 0xb0)) {
				/* Compress source and dest ports. */
				buffer[ieee_header_len + lowpan6_header_len++] |= 0x03;
				buffer[ieee_header_len + lowpan6_header_len++] = ((((u8_t*)p->payload)[1] & 0x0f) << 4) | (((u8_t*)p->payload)[3] & 0x0f);
			} else if(((u8_t*)p->payload)[0] == 0xf0) {
				/* Compress source port. */
				buffer[ieee_header_len + lowpan6_header_len++] |= 0x02;
				buffer[ieee_header_len + lowpan6_header_len++] = ((u8_t*)p->payload)[1];
				buffer[ieee_header_len + lowpan6_header_len++] = ((u8_t*)p->payload)[2];
				buffer[ieee_header_len + lowpan6_header_len++] = ((u8_t*)p->payload)[3];
			} else if(((u8_t*)p->payload)[2] == 0xf0) {
				/* Compress dest port. */
				buffer[ieee_header_len + lowpan6_header_len++] |= 0x01;
				buffer[ieee_header_len + lowpan6_header_len++] = ((u8_t*)p->payload)[0];
				buffer[ieee_header_len + lowpan6_header_len++] = ((u8_t*)p->payload)[1];
				buffer[ieee_header_len + lowpan6_header_len++] = ((u8_t*)p->payload)[3];
			} else {
				/* append full ports. */
				lowpan6_header_len++;
				buffer[ieee_header_len + lowpan6_header_len++] = ((u8_t*)p->payload)[0];
				buffer[ieee_header_len + lowpan6_header_len++] = ((u8_t*)p->payload)[1];
				buffer[ieee_header_len + lowpan6_header_len++] = ((u8_t*)p->payload)[2];
				buffer[ieee_header_len + lowpan6_header_len++] = ((u8_t*)p->payload)[3];
			}

			/* elide length and copy checksum */
			buffer[ieee_header_len + lowpan6_header_len++] = ((u8_t*)p->payload)[6];
			buffer[ieee_header_len + lowpan6_header_len++] = ((u8_t*)p->payload)[7];

			pbuf_header(p, -UDP_HLEN);
		}
	}

#else /* LWIP_6LOWPAN_HC */
	/* Send uncompressed IPv6 header with appropriate dispatch byte. */
	lowpan6_header_len = 1;
	buffer[ieee_header_len] = 0x41; /* IPv6 dispatch */
#endif /* LWIP_6LOWPAN_HC */

	/* Calculate remaining packet length */
	remaining_len = p->tot_len;

	if(remaining_len > 0x7FF) {
		MIB2_STATS_NETIF_INC(netif, ifoutdiscards);
		/* datagram_size must fit into 11 bit */
		pbuf_free(p_frag);
		return ERR_VAL;
	}

	/* Fragment, or 1 packet? */
	if(remaining_len > (127 - ieee_header_len - lowpan6_header_len - 3)) {  /* 127 - header - 1 byte dispatch - 2 bytes CRC */
		/* We must move the 6LowPAN header to make room for the FRAG header. */
		i = lowpan6_header_len;

		while(i-- != 0) {
			buffer[ieee_header_len + i + 4] = buffer[ieee_header_len + i];
		}

		/* Now we need to fragment the packet. FRAG1 header first */
		buffer[ieee_header_len] = 0xc0 | (((p->tot_len + lowpan6_header_len) >> 8) & 0x7);
		buffer[ieee_header_len + 1] = (p->tot_len + lowpan6_header_len) & 0xff;

		datagram_tag++;
		buffer[ieee_header_len + 2] = datagram_tag & 0xff;
		buffer[ieee_header_len + 3] = (datagram_tag >> 8) & 0xff;

		/* Fragment follows. */
		frag_len = (127 - ieee_header_len - 4 - 2) & 0xf8;

		pbuf_copy_partial(p, buffer + ieee_header_len + lowpan6_header_len + 4, frag_len - lowpan6_header_len, 0);
		remaining_len -= frag_len - lowpan6_header_len;
		datagram_offset = frag_len;

		/* 2 bytes CRC */
#if LWIP_6LOWPAN_HW_CRC
		/* Leave blank, will be filled by HW. */
#else /* LWIP_6LOWPAN_HW_CRC */
		/* @todo calculate CRC */
#endif /* LWIP_6LOWPAN_HW_CRC */

		/* Calculate frame length */
		p_frag->len = p_frag->tot_len = ieee_header_len + 4 + frag_len + 2; /* add 2 dummy bytes for crc*/

		/* send the packet */
		MIB2_STATS_NETIF_ADD(netif, ifoutoctets, p_frag->tot_len);
		LWIP_DEBUGF(LOWPAN6_DEBUG | LWIP_DBG_TRACE, ("lowpan6_send: sending packet %p\n", (void*)p));
		err = netif->linkoutput(netif, p_frag);

		while((remaining_len > 0) && (err == ERR_OK)) {
			/* new frame, new seq num for ACK */
			buffer[2] = frame_seq_num++;

			buffer[ieee_header_len] |= 0x20; /* Change FRAG1 to FRAGN */

			buffer[ieee_header_len + 4] = (u8_t)(datagram_offset >> 3); /* datagram offset in FRAGN header (datagram_offset is max. 11 bit) */

			frag_len = (127 - ieee_header_len - 5 - 2) & 0xf8;

			if(frag_len > remaining_len) {
				frag_len = remaining_len;
			}

			pbuf_copy_partial(p, buffer + ieee_header_len + 5, frag_len, p->tot_len - remaining_len);
			remaining_len -= frag_len;
			datagram_offset += frag_len;

			/* 2 bytes CRC */
#if LWIP_6LOWPAN_HW_CRC
			/* Leave blank, will be filled by HW. */
#else /* LWIP_6LOWPAN_HW_CRC */
			/* @todo calculate CRC */
#endif /* LWIP_6LOWPAN_HW_CRC */

			/* Calculate frame length */
			p_frag->len = p_frag->tot_len = frag_len + 5 + ieee_header_len + 2;

			/* send the packet */
			MIB2_STATS_NETIF_ADD(netif, ifoutoctets, p_frag->tot_len);
			LWIP_DEBUGF(LOWPAN6_DEBUG | LWIP_DBG_TRACE, ("lowpan6_send: sending packet %p\n", (void*)p));
			err = netif->linkoutput(netif, p_frag);
		}
	} else {
		/* It fits in one frame. */
		frag_len = remaining_len;

		/* Copy IPv6 packet */
		pbuf_copy_partial(p, buffer + ieee_header_len + lowpan6_header_len, frag_len, 0);
		remaining_len = 0;

		/* 2 bytes CRC */
#if LWIP_6LOWPAN_HW_CRC
		/* Leave blank, will be filled by HW. */
#else /* LWIP_6LOWPAN_HW_CRC */
		/* @todo calculate CRC */
#endif /* LWIP_6LOWPAN_HW_CRC */

		/* Calculate frame length */
		p_frag->len = p_frag->tot_len = frag_len + lowpan6_header_len + ieee_header_len + 2;

		/* send the packet */
		MIB2_STATS_NETIF_ADD(netif, ifoutoctets, p_frag->tot_len);
		LWIP_DEBUGF(LOWPAN6_DEBUG | LWIP_DBG_TRACE, ("lowpan6_send: sending packet %p\n", (void*)p));
		err = netif->linkoutput(netif, p_frag);
	}

	pbuf_free(p_frag);

	return err;
}

err_t
lowpan6_set_context(u8_t idx, const ip6_addr_t* context)
{
	if(idx >= LWIP_6LOWPAN_NUM_CONTEXTS) {
		return ERR_ARG;
	}

	ip6_addr_set(&lowpan6_context[idx], context);

	return ERR_OK;
}

#if LWIP_6LOWPAN_INFER_SHORT_ADDRESS
err_t
lowpan6_set_short_addr(u8_t addr_high, u8_t addr_low)
{
	short_mac_addr.addr[0] = addr_high;
	short_mac_addr.addr[1] = addr_low;

	return ERR_OK;
}
#endif /* LWIP_6LOWPAN_INFER_SHORT_ADDRESS */

#if LWIP_IPV4
err_t
lowpan4_output(struct netif* netif, struct pbuf* q, const ip4_addr_t* ipaddr)
{
	(void)netif;
	(void)q;
	(void)ipaddr;

	return ERR_IF;
}
#endif /* LWIP_IPV4 */

/**
 * Resolve and fill-in IEEE 802.15.4 address header for outgoing IPv6 packet.
 *
 * Perform Header Compression and fragment if necessary.
 *
 * @param netif The lwIP network interface which the IP packet will be sent on.
 * @param q The pbuf(s) containing the IP packet to be sent.
 * @param ip6addr The IP address of the packet destination.
 *
 * @return err_t
 */
err_t
lowpan6_output(struct netif* netif, struct pbuf* q, const ip6_addr_t* ip6addr)
{
	err_t result;
	const u8_t* hwaddr;
	struct ieee_802154_addr src, dest;
#if LWIP_6LOWPAN_INFER_SHORT_ADDRESS
	ip6_addr_t ip6_src;
	struct ip6_hdr* ip6_hdr;
#endif /* LWIP_6LOWPAN_INFER_SHORT_ADDRESS */

#if LWIP_6LOWPAN_INFER_SHORT_ADDRESS
	/* Check if we can compress source address (use aligned copy) */
	ip6_hdr = (struct ip6_hdr*)q->payload;
	ip6_addr_set(&ip6_src, &ip6_hdr->src);

	if(lowpan6_get_address_mode(&ip6_src, &short_mac_addr) == 3) {
		src.addr_len = 2;
		src.addr[0] = short_mac_addr.addr[0];
		src.addr[1] = short_mac_addr.addr[1];
	} else
#endif /* LWIP_6LOWPAN_INFER_SHORT_ADDRESS */
	{
		src.addr_len = netif->hwaddr_len;
		SMEMCPY(src.addr, netif->hwaddr, netif->hwaddr_len);
	}

	/* multicast destination IP address? */
	if(ip6_addr_ismulticast(ip6addr)) {
		MIB2_STATS_NETIF_INC(netif, ifoutnucastpkts);
		/* We need to send to the broadcast address.*/
		return lowpan6_frag(netif, q, &src, &ieee_802154_broadcast);
	}

	/* We have a unicast destination IP address */
	/* @todo anycast? */

#if LWIP_6LOWPAN_INFER_SHORT_ADDRESS

	if(src.addr_len == 2) {
		/* If source address was compressable to short_mac_addr, and dest has same subnet and
		* is also compressable to 2-bytes, assume we can infer dest as a short address too. */
		dest.addr_len = 2;
		dest.addr[0] = ((u8_t*)q->payload)[38];
		dest.addr[1] = ((u8_t*)q->payload)[39];

		if((src.addr_len == 2) && (ip6_addr_netcmp(&ip6_hdr->src, &ip6_hdr->dest)) &&
		        (lowpan6_get_address_mode(ip6addr, &dest) == 3)) {
			MIB2_STATS_NETIF_INC(netif, ifoutucastpkts);
			return lowpan6_frag(netif, q, &src, &dest);
		}
	}

#endif /* LWIP_6LOWPAN_INFER_SHORT_ADDRESS */

	/* Ask ND6 what to do with the packet. */
	result = nd6_get_next_hop_addr_or_queue(netif, q, ip6addr, &hwaddr);

	if(result != ERR_OK) {
		MIB2_STATS_NETIF_INC(netif, ifoutdiscards);
		return result;
	}

	/* If no hardware address is returned, nd6 has queued the packet for later. */
	if(hwaddr == NULL) {
		return ERR_OK;
	}

	/* Send out the packet using the returned hardware address. */
	dest.addr_len = netif->hwaddr_len;
	SMEMCPY(dest.addr, hwaddr, netif->hwaddr_len);
	MIB2_STATS_NETIF_INC(netif, ifoutucastpkts);
	return lowpan6_frag(netif, q, &src, &dest);
}

static struct pbuf*
lowpan6_decompress(struct pbuf* p, struct ieee_802154_addr* src, struct ieee_802154_addr* dest)
{
	struct pbuf* q;
	u8_t* lowpan6_buffer;
	s8_t lowpan6_offset;
	struct ip6_hdr* ip6hdr;
	s8_t i;
	s8_t ip6_offset = IP6_HLEN;


	q = pbuf_alloc(PBUF_IP, p->len + IP6_HLEN + UDP_HLEN, PBUF_POOL);

	if(q == NULL) {
		pbuf_free(p);
		return NULL;
	}

	lowpan6_buffer = (u8_t*)p->payload;
	ip6hdr = (struct ip6_hdr*)q->payload;

	lowpan6_offset = 2;

	if(lowpan6_buffer[1] & 0x80) {
		lowpan6_offset++;
	}

	/* Set IPv6 version, traffic class and flow label. */
	if((lowpan6_buffer[0] & 0x18) == 0x00) {
		IP6H_VTCFL_SET(ip6hdr, 6, lowpan6_buffer[lowpan6_offset], ((lowpan6_buffer[lowpan6_offset + 1] & 0x0f) << 16) | (lowpan6_buffer[lowpan6_offset + 2] << 8) | lowpan6_buffer[lowpan6_offset + 3]);
		lowpan6_offset += 4;
	} else if((lowpan6_buffer[0] & 0x18) == 0x08) {
		IP6H_VTCFL_SET(ip6hdr, 6, lowpan6_buffer[lowpan6_offset] & 0xc0, ((lowpan6_buffer[lowpan6_offset] & 0x0f) << 16) | (lowpan6_buffer[lowpan6_offset + 1] << 8) | lowpan6_buffer[lowpan6_offset + 2]);
		lowpan6_offset += 3;
	} else if((lowpan6_buffer[0] & 0x18) == 0x10) {
		IP6H_VTCFL_SET(ip6hdr, 6, lowpan6_buffer[lowpan6_offset], 0);
		lowpan6_offset += 1;
	} else if((lowpan6_buffer[0] & 0x18) == 0x18) {
		IP6H_VTCFL_SET(ip6hdr, 6, 0, 0);
	}

	/* Set Next Header */
	if((lowpan6_buffer[0] & 0x04) == 0x00) {
		IP6H_NEXTH_SET(ip6hdr, lowpan6_buffer[lowpan6_offset++]);
	} else {
		/* We should fill this later with NHC decoding */
		IP6H_NEXTH_SET(ip6hdr, 0);
	}

	/* Set Hop Limit */
	if((lowpan6_buffer[0] & 0x03) == 0x00) {
		IP6H_HOPLIM_SET(ip6hdr, lowpan6_buffer[lowpan6_offset++]);
	} else if((lowpan6_buffer[0] & 0x03) == 0x01) {
		IP6H_HOPLIM_SET(ip6hdr, 1);
	} else if((lowpan6_buffer[0] & 0x03) == 0x02) {
		IP6H_HOPLIM_SET(ip6hdr, 64);
	} else if((lowpan6_buffer[0] & 0x03) == 0x03) {
		IP6H_HOPLIM_SET(ip6hdr, 255);
	}

	/* Source address decoding. */
	if((lowpan6_buffer[1] & 0x40) == 0x00) {
		/* Stateless compression */
		if((lowpan6_buffer[1] & 0x30) == 0x00) {
			/* copy full address */
			MEMCPY(&ip6hdr->src.addr[0], lowpan6_buffer + lowpan6_offset, 16);
			lowpan6_offset += 16;
		} else if((lowpan6_buffer[1] & 0x30) == 0x10) {
			ip6hdr->src.addr[0] = PP_HTONL(0xfe800000UL);
			ip6hdr->src.addr[1] = 0;
			MEMCPY(&ip6hdr->src.addr[2], lowpan6_buffer + lowpan6_offset, 8);
			lowpan6_offset += 8;
		} else if((lowpan6_buffer[1] & 0x30) == 0x20) {
			ip6hdr->src.addr[0] = PP_HTONL(0xfe800000UL);
			ip6hdr->src.addr[1] = 0;
			ip6hdr->src.addr[2] = PP_HTONL(0x000000ffUL);
			ip6hdr->src.addr[3] = lwip_htonl(0xfe000000UL | (lowpan6_buffer[lowpan6_offset] << 8) |
			                                 lowpan6_buffer[lowpan6_offset + 1]);
			lowpan6_offset += 2;
		} else if((lowpan6_buffer[1] & 0x30) == 0x30) {
			ip6hdr->src.addr[0] = PP_HTONL(0xfe800000UL);
			ip6hdr->src.addr[1] = 0;

			if(src->addr_len == 2) {
				ip6hdr->src.addr[2] = PP_HTONL(0x000000ffUL);
				ip6hdr->src.addr[3] = lwip_htonl(0xfe000000UL | (src->addr[0] << 8) | src->addr[1]);
			} else {
				ip6hdr->src.addr[2] = lwip_htonl(((src->addr[0] ^ 2) << 24) | (src->addr[1] << 16) |
				                                 (src->addr[2] << 8) | src->addr[3]);
				ip6hdr->src.addr[3] = lwip_htonl((src->addr[4] << 24) | (src->addr[5] << 16) |
				                                 (src->addr[6] << 8) | src->addr[7]);
			}
		}
	} else {
		/* Stateful compression */
		if((lowpan6_buffer[1] & 0x30) == 0x00) {
			/* ANY address */
			ip6hdr->src.addr[0] = 0;
			ip6hdr->src.addr[1] = 0;
			ip6hdr->src.addr[2] = 0;
			ip6hdr->src.addr[3] = 0;
		} else {
			/* Set prefix from context info */
			if(lowpan6_buffer[1] & 0x80) {
				i = (lowpan6_buffer[2] >> 4) & 0x0f;
			} else {
				i = 0;
			}

			if(i >= LWIP_6LOWPAN_NUM_CONTEXTS) {
				/* Error */
				pbuf_free(p);
				pbuf_free(q);
				return NULL;
			}

			ip6hdr->src.addr[0] = lowpan6_context[i].addr[0];
			ip6hdr->src.addr[1] = lowpan6_context[i].addr[1];
		}

		if((lowpan6_buffer[1] & 0x30) == 0x10) {
			MEMCPY(&ip6hdr->src.addr[2], lowpan6_buffer + lowpan6_offset, 8);
			lowpan6_offset += 8;
		} else if((lowpan6_buffer[1] & 0x30) == 0x20) {
			ip6hdr->src.addr[2] = PP_HTONL(0x000000ffUL);
			ip6hdr->src.addr[3] = lwip_htonl(0xfe000000UL | (lowpan6_buffer[lowpan6_offset] << 8) | lowpan6_buffer[lowpan6_offset + 1]);
			lowpan6_offset += 2;
		} else if((lowpan6_buffer[1] & 0x30) == 0x30) {
			if(src->addr_len == 2) {
				ip6hdr->src.addr[2] = PP_HTONL(0x000000ffUL);
				ip6hdr->src.addr[3] = lwip_htonl(0xfe000000UL | (src->addr[0] << 8) | src->addr[1]);
			} else {
				ip6hdr->src.addr[2] = lwip_htonl(((src->addr[0] ^ 2) << 24) | (src->addr[1] << 16) | (src->addr[2] << 8) | src->addr[3]);
				ip6hdr->src.addr[3] = lwip_htonl((src->addr[4] << 24) | (src->addr[5] << 16) | (src->addr[6] << 8) | src->addr[7]);
			}
		}
	}

	/* Destination address decoding. */
	if(lowpan6_buffer[1] & 0x08) {
		/* Multicast destination */
		if(lowpan6_buffer[1] & 0x04) {
			/* @todo support stateful multicast addressing */
			pbuf_free(p);
			pbuf_free(q);
			return NULL;
		}

		if((lowpan6_buffer[1] & 0x03) == 0x00) {
			/* copy full address */
			MEMCPY(&ip6hdr->dest.addr[0], lowpan6_buffer + lowpan6_offset, 16);
			lowpan6_offset += 16;
		} else if((lowpan6_buffer[1] & 0x03) == 0x01) {
			ip6hdr->dest.addr[0] = lwip_htonl(0xff000000UL | (lowpan6_buffer[lowpan6_offset++] << 16));
			ip6hdr->dest.addr[1] = 0;
			ip6hdr->dest.addr[2] = lwip_htonl(lowpan6_buffer[lowpan6_offset++]);
			ip6hdr->dest.addr[3] = lwip_htonl((lowpan6_buffer[lowpan6_offset] << 24) | (lowpan6_buffer[lowpan6_offset + 1] << 16) | (lowpan6_buffer[lowpan6_offset + 2] << 8) | lowpan6_buffer[lowpan6_offset + 3]);
			lowpan6_offset += 4;
		} else if((lowpan6_buffer[1] & 0x03) == 0x02) {
			ip6hdr->dest.addr[0] = lwip_htonl(0xff000000UL | lowpan6_buffer[lowpan6_offset++]);
			ip6hdr->dest.addr[1] = 0;
			ip6hdr->dest.addr[2] = 0;
			ip6hdr->dest.addr[3] = lwip_htonl((lowpan6_buffer[lowpan6_offset] << 16) | (lowpan6_buffer[lowpan6_offset + 1] << 8) | lowpan6_buffer[lowpan6_offset + 2]);
			lowpan6_offset += 3;
		} else if((lowpan6_buffer[1] & 0x03) == 0x03) {
			ip6hdr->dest.addr[0] = PP_HTONL(0xff020000UL);
			ip6hdr->dest.addr[1] = 0;
			ip6hdr->dest.addr[2] = 0;
			ip6hdr->dest.addr[3] = lwip_htonl(lowpan6_buffer[lowpan6_offset++]);
		}

	} else {
		if(lowpan6_buffer[1] & 0x04) {
			/* Stateful destination compression */
			/* Set prefix from context info */
			if(lowpan6_buffer[1] & 0x80) {
				i = lowpan6_buffer[2] & 0x0f;
			} else {
				i = 0;
			}

			if(i >= LWIP_6LOWPAN_NUM_CONTEXTS) {
				/* Error */
				pbuf_free(p);
				pbuf_free(q);
				return NULL;
			}

			ip6hdr->dest.addr[0] = lowpan6_context[i].addr[0];
			ip6hdr->dest.addr[1] = lowpan6_context[i].addr[1];
		} else {
			/* Link local address compression */
			ip6hdr->dest.addr[0] = PP_HTONL(0xfe800000UL);
			ip6hdr->dest.addr[1] = 0;
		}

		if((lowpan6_buffer[1] & 0x03) == 0x00) {
			/* copy full address */
			MEMCPY(&ip6hdr->dest.addr[0], lowpan6_buffer + lowpan6_offset, 16);
			lowpan6_offset += 16;
		} else if((lowpan6_buffer[1] & 0x03) == 0x01) {
			MEMCPY(&ip6hdr->dest.addr[2], lowpan6_buffer + lowpan6_offset, 8);
			lowpan6_offset += 8;
		} else if((lowpan6_buffer[1] & 0x03) == 0x02) {
			ip6hdr->dest.addr[2] = PP_HTONL(0x000000ffUL);
			ip6hdr->dest.addr[3] = lwip_htonl(0xfe000000UL | (lowpan6_buffer[lowpan6_offset] << 8) | lowpan6_buffer[lowpan6_offset + 1]);
			lowpan6_offset += 2;
		} else if((lowpan6_buffer[1] & 0x03) == 0x03) {
			if(dest->addr_len == 2) {
				ip6hdr->dest.addr[2] = PP_HTONL(0x000000ffUL);
				ip6hdr->dest.addr[3] = lwip_htonl(0xfe000000UL | (dest->addr[0] << 8) | dest->addr[1]);
			} else {
				ip6hdr->dest.addr[2] = lwip_htonl(((dest->addr[0] ^ 2) << 24) | (dest->addr[1] << 16) | dest->addr[2] << 8 | dest->addr[3]);
				ip6hdr->dest.addr[3] = lwip_htonl((dest->addr[4] << 24) | (dest->addr[5] << 16) | dest->addr[6] << 8 | dest->addr[7]);
			}
		}
	}


	/* Next Header Compression (NHC) decoding? */
	if(lowpan6_buffer[0] & 0x04) {
		if((lowpan6_buffer[lowpan6_offset] & 0xf8) == 0xf0) {
			struct udp_hdr* udphdr;

			/* UDP compression */
			IP6H_NEXTH_SET(ip6hdr, IP6_NEXTH_UDP);
			udphdr = (struct udp_hdr*)((u8_t*)q->payload + ip6_offset);

			if(lowpan6_buffer[lowpan6_offset] & 0x04) {
				/* @todo support checksum decompress */
				pbuf_free(p);
				pbuf_free(q);
				return NULL;
			}

			/* Decompress ports */
			i = lowpan6_buffer[lowpan6_offset++] & 0x03;

			if(i == 0) {
				udphdr->src = lwip_htons(lowpan6_buffer[lowpan6_offset] << 8 | lowpan6_buffer[lowpan6_offset + 1]);
				udphdr->dest = lwip_htons(lowpan6_buffer[lowpan6_offset + 2] << 8 | lowpan6_buffer[lowpan6_offset + 3]);
				lowpan6_offset += 4;
			} else if(i == 0x01) {
				udphdr->src = lwip_htons(lowpan6_buffer[lowpan6_offset] << 8 | lowpan6_buffer[lowpan6_offset + 1]);
				udphdr->dest = lwip_htons(0xf000 | lowpan6_buffer[lowpan6_offset + 2]);
				lowpan6_offset += 3;
			} else if(i == 0x02) {
				udphdr->src = lwip_htons(0xf000 | lowpan6_buffer[lowpan6_offset]);
				udphdr->dest = lwip_htons(lowpan6_buffer[lowpan6_offset + 1] << 8 | lowpan6_buffer[lowpan6_offset + 2]);
				lowpan6_offset += 3;
			} else if(i == 0x03) {
				udphdr->src = lwip_htons(0xf0b0 | ((lowpan6_buffer[lowpan6_offset] >> 4) & 0x0f));
				udphdr->dest = lwip_htons(0xf0b0 | (lowpan6_buffer[lowpan6_offset] & 0x0f));
				lowpan6_offset += 1;
			}

			udphdr->chksum = lwip_htons(lowpan6_buffer[lowpan6_offset] << 8 | lowpan6_buffer[lowpan6_offset + 1]);
			lowpan6_offset += 2;
			udphdr->len = lwip_htons(p->tot_len - lowpan6_offset + UDP_HLEN);

			ip6_offset += UDP_HLEN;
		} else {
			/* @todo support NHC other than UDP */
			pbuf_free(p);
			pbuf_free(q);
			return NULL;
		}
	}

	/* Now we copy leftover contents from p to q, so we have all L2 and L3 headers (and L4?) in a single PBUF.
	* Replace p with q, and free p */
	pbuf_header(p, -lowpan6_offset);
	MEMCPY((u8_t*)q->payload + ip6_offset, p->payload, p->len);
	q->len = q->tot_len = ip6_offset + p->len;

	if(p->next != NULL) {
		pbuf_cat(q, p->next);
	}

	p->next = NULL;
	pbuf_free(p);

	/* Infer IPv6 payload length for header */
	IP6H_PLEN_SET(ip6hdr, q->tot_len - IP6_HLEN);

	/* all done */
	return q;
}

err_t
lowpan6_input(struct pbuf* p, struct netif* netif)
{
	u8_t* puc;
	s8_t i;
	struct ieee_802154_addr src, dest;
	u16_t datagram_size, datagram_offset, datagram_tag;
	struct lowpan6_reass_helper* lrh, *lrh_temp;

	MIB2_STATS_NETIF_ADD(netif, ifinoctets, p->tot_len);

	/* Analyze header. @todo validate. */
	puc = (u8_t*)p->payload;
	datagram_offset = 5;

	if((puc[1] & 0x0c) == 0x0c) {
		dest.addr_len = 8;

		for(i = 0; i < 8; i++) {
			dest.addr[i] = puc[datagram_offset + 7 - i];
		}

		datagram_offset += 8;
	} else {
		dest.addr_len = 2;
		dest.addr[0] = puc[datagram_offset + 1];
		dest.addr[1] = puc[datagram_offset];
		datagram_offset += 2;
	}

	datagram_offset += 2; /* skip PAN ID. */

	if((puc[1] & 0xc0) == 0xc0) {
		src.addr_len = 8;

		for(i = 0; i < 8; i++) {
			src.addr[i] = puc[datagram_offset + 7 - i];
		}

		datagram_offset += 8;
	} else {
		src.addr_len = 2;
		src.addr[0] = puc[datagram_offset + 1];
		src.addr[1] = puc[datagram_offset];
		datagram_offset += 2;
	}

	pbuf_header(p, -datagram_offset); /* hide IEEE802.15.4 header. */

	/* Check dispatch. */
	puc = (u8_t*)p->payload;

	if((*puc & 0xf8) == 0xc0) {
		/* FRAG1 dispatch. add this packet to reassembly list. */
		datagram_size = ((u16_t)(puc[0] & 0x07) << 8) | (u16_t)puc[1];
		datagram_tag = ((u16_t)puc[2] << 8) | (u16_t)puc[3];

		/* check for duplicate */
		lrh = reass_list;

		while(lrh != NULL) {
			if((lrh->sender_addr.addr_len == src.addr_len) &&
			        (memcmp(lrh->sender_addr.addr, src.addr, src.addr_len) == 0)) {
				/* address match with packet in reassembly. */
				if((datagram_tag == lrh->datagram_tag) && (datagram_size == lrh->datagram_size)) {
					MIB2_STATS_NETIF_INC(netif, ifindiscards);
					/* duplicate fragment. */
					pbuf_free(p);
					return ERR_OK;
				} else {
					/* We are receiving the start of a new datagram. Discard old one (incomplete). */
					lrh_temp = lrh->next_packet;
					dequeue_datagram(lrh);
					pbuf_free(lrh->pbuf);
					mem_free(lrh);

					/* Check next datagram in queue. */
					lrh = lrh_temp;
				}
			} else {
				/* Check next datagram in queue. */
				lrh = lrh->next_packet;
			}
		}

		pbuf_header(p, -4); /* hide frag1 dispatch */

		lrh = (struct lowpan6_reass_helper*) mem_malloc(sizeof(struct lowpan6_reass_helper));

		if(lrh == NULL) {
			MIB2_STATS_NETIF_INC(netif, ifindiscards);
			pbuf_free(p);
			return ERR_MEM;
		}

		lrh->sender_addr.addr_len = src.addr_len;

		for(i = 0; i < src.addr_len; i++) {
			lrh->sender_addr.addr[i] = src.addr[i];
		}

		lrh->datagram_size = datagram_size;
		lrh->datagram_tag = datagram_tag;
		lrh->pbuf = p;
		lrh->next_packet = reass_list;
		lrh->timer = 2;
		reass_list = lrh;

		return ERR_OK;
	} else if((*puc & 0xf8) == 0xe0) {
		/* FRAGN dispatch, find packet being reassembled. */
		datagram_size = ((u16_t)(puc[0] & 0x07) << 8) | (u16_t)puc[1];
		datagram_tag = ((u16_t)puc[2] << 8) | (u16_t)puc[3];
		datagram_offset = (u16_t)puc[4] << 3;
		pbuf_header(p, -5); /* hide frag1 dispatch */

		for(lrh = reass_list; lrh != NULL; lrh = lrh->next_packet) {
			if((lrh->sender_addr.addr_len == src.addr_len) &&
			        (memcmp(lrh->sender_addr.addr, src.addr, src.addr_len) == 0) &&
			        (datagram_tag == lrh->datagram_tag) &&
			        (datagram_size == lrh->datagram_size)) {
				break;
			}
		}

		if(lrh == NULL) {
			/* rogue fragment */
			MIB2_STATS_NETIF_INC(netif, ifindiscards);
			pbuf_free(p);
			return ERR_OK;
		}

		if(lrh->pbuf->tot_len < datagram_offset) {
			/* duplicate, ignore. */
			pbuf_free(p);
			return ERR_OK;
		} else if(lrh->pbuf->tot_len > datagram_offset) {
			MIB2_STATS_NETIF_INC(netif, ifindiscards);
			/* We have missed a fragment. Delete whole reassembly. */
			dequeue_datagram(lrh);
			pbuf_free(lrh->pbuf);
			mem_free(lrh);
			pbuf_free(p);
			return ERR_OK;
		}

		pbuf_cat(lrh->pbuf, p);
		p = NULL;

		/* is packet now complete?*/
		if(lrh->pbuf->tot_len >= lrh->datagram_size) {
			/* dequeue from reass list. */
			dequeue_datagram(lrh);

			/* get pbuf */
			p = lrh->pbuf;

			/* release helper */
			mem_free(lrh);
		} else {
			return ERR_OK;
		}
	}

	if(p == NULL) {
		return ERR_OK;
	}

	/* We have a complete packet, check dispatch for headers. */
	puc = (u8_t*)p->payload;

	if(*puc == 0x41) {
		/* This is a complete IPv6 packet, just skip dispatch byte. */
		pbuf_header(p, -1); /* hide dispatch byte. */
	} else if((*puc & 0xe0) == 0x60) {
		/* IPv6 headers are compressed using IPHC. */
		p = lowpan6_decompress(p, &src, &dest);

		if(p == NULL) {
			MIB2_STATS_NETIF_INC(netif, ifindiscards);
			return ERR_OK;
		}
	} else {
		MIB2_STATS_NETIF_INC(netif, ifindiscards);
		pbuf_free(p);
		return ERR_OK;
	}

	/* @todo: distinguish unicast/multicast */
	MIB2_STATS_NETIF_INC(netif, ifinucastpkts);

	return ip6_input(p, netif);
}

err_t
lowpan6_if_init(struct netif* netif)
{
	netif->name[0] = 'L';
	netif->name[1] = '6';
#if LWIP_IPV4
	netif->output = lowpan4_output;
#endif /* LWIP_IPV4 */
	netif->output_ip6 = lowpan6_output;

	MIB2_INIT_NETIF(netif, snmp_ifType_other, 0);

	/* maximum transfer unit */
	netif->mtu = 1280;

	/* broadcast capability */
	netif->flags = NETIF_FLAG_BROADCAST /* | NETIF_FLAG_LOWPAN6 */;

	return ERR_OK;
}

err_t
lowpan6_set_pan_id(u16_t pan_id)
{
	ieee_802154_pan_id = pan_id;

	return ERR_OK;
}

#if !NO_SYS
/**
 * Pass a received packet to tcpip_thread for input processing
 *
 * @param p the received packet, p->payload pointing to the
 *          IEEE 802.15.4 header.
 * @param inp the network interface on which the packet was received
 */
err_t
tcpip_6lowpan_input(struct pbuf* p, struct netif* inp)
{
	return tcpip_inpkt(p, inp, lowpan6_input);
}
#endif /* !NO_SYS */

#endif /* LWIP_IPV6 && LWIP_6LOWPAN */
